New setup - loud chattering from right side ball screw nut?

Community Support ❓ Something's Up
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I have a brand new AltMill 2x4 setup. I was just preparing to surface the spoil board, and then found a very loud chattering coming from what appears to be the right side ball screw nut.it only occurs when the y axis is in certain spots ( it happens on most of it), and only at higher traverse speeds. It sounds horrible, and unhealthy, so I did not proceed with the surfacing, and have been trying to dog into troubleshooting first,

1 - only a higher speeds. When on “precise” speed, it makes not a sound.

2 - only certain areas of the y axis. It’s not along the ENTIRE screw, but does seem to happen along most of it,

3 - I tried to hold a runout gauge on the screw in the trouble spot, and it appears to be “out” by about 10-12 thou measured at the outer diameter of the screw - doesn’t seem that much, but is that within tolerances?

4 - when I opened up the y rails from the packaging, out rolled 3 small ball bearings, which look to be the same as what is in the guide bearings. Inspecting the guide bearings, I didn’t observe anything wrong. An email to Support got the response of “probably just loose bearings somehow got into my packaging”. The guide bearings seemed to be ok.

5 - the right y axis motor got pretty hot during this initial test, I switched it out with the x axis motor and all seems ok temp-wise since then.

6 - I loosened the 4 screws attaching the gantry to the ball screw nut, and that yielded a pop, like the gantry must have been torqued a bit somehow. I adjusted the position of the ball screw nut and re-attached, but the noise remains.

Further testing doing the “outline” of the spoil board run still gives me that loud chattering coming that I’m uneasy with… any ideas? Has anybody else had this sort of issue? I’m so close to making dust, but this thing just isn’t cooperating.

I think its a bearing problem
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@Ninefingers You should open a support ticket with Sienci.

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I will, but it’s Saturday… was hoping maybe somebody here would have an idea…

1 Like
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I had the same issue when I set mine up. After reading through a few posts, I found the solution. The screws holding the ball screw nut were simply not tight enough. I tightened them and voilá, problem solved. FWIW, I also went around and checked all the screws and the bearing cars also.

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I second this - I found that after double checking all the screws (gantry, guides, stringers…,), a couple weren’t more than finger tight. The symptom was resonance and unexpectedly loud operation.

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My Altmill makes all sorts of noises/vibrations when moving along the x or y axis. That said it cuts great and all my projects have turned out flawless. Except for that one-time gSender froze while I was jogging my Z down and it plunged through my workpiece.

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As someone who is new to ball screws. Which screws specifically needed to be tightened?

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The screws I missed were the ones that connect the gantry plates to the rail bearings and ball screw nut

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Ah okay all the screws in the plates are tight. Wasn’t sure if these were screws holding the ball nuts together or something.

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Is the noise coming from a particular place - such as the pillow blocks at the end of the ball screw, the left or right Y or cross gantry X ball nuts, or bearings?

If these ball bearings did indeed come from a rail bearing assembly, then slop in the bearing race could be the source.

I’d be more inclined to believe “probably just loose bearings somehow got into my packaging”. if you didn’t also have this problem :slight_smile:

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The sound appears to be coming from the screw nut on the gantry. The rail bearings seemed to operate ok, and I didn’t see any missing ball bearings when I inspected them. So far, support has been unable to determine the issue, but I will say they’re going extremely slow in trying to resolve.

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I had a similar loud clunk noise coming from around the right Y axis whenever I move the Gantry along the Y-axis starting at the Home position. The culprit was the X-axis ball screw bearing holder screws not tightened down.

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Continuing to try to debug, I found that the right side mount of the ball screw nut to the gantry is a nice tight fit, while the left side is loose. Oddly, the right side is where the noise is. I tried to loosen everything up, to reseat the ball screw nuts on both sides, but same outcome.

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Sad update - I tried reaching out to support directly by phone - I was told that my rate of progress while working with them on this was as good as it was going to get. At this point, I’m sorry I went down the path with this particular vendor. 1 month in, and I’m still unable to use the machine.

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Time to take a good serving of humble pie.

Customers Support suggested today that I check that I used the correct screw to mount the gantry to the screw nut… turns out I used 20mm rather than 16mm screws, so the nut never was seated properly to the gantry. Lo and behold, I now have a virtually noise-free gantry jog! Sawdust will commence tomorrow morning!

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@Ninefingers I think no one responded to your post yesterday because most people who come here are quite satisfied with Sienci and Sienci Tech support. I guess people didn’t know what to say to you. At least now, my opinion of them hasn’t changed.

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Ya - I was pretty certain I had done something wrong - it was just a matter of getting to the issue. I vented a bit of frustration with it taking a while to get to… and I’m now embarrassed that I did that. But, having gotten there, I can now try to channel more positivity going forward.

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@Ninefingers Well said, Dave. Go forth and carve.